This document specifies requirements for the structure and expression of an architecture description (AD) for various entities, including software, systems, enterprises, systems of systems, families of systems, products (goods or services), product lines, service lines, technologies and business domains. This document distinguishes the architecture of an entity of interest from an AD expressing that architecture. Architectures are not the subject of this document. This document specifies requirements for use of the architectural concepts and their relationships as captured in an AD. It does not specify requirements for any entity of interest or its environment. This document specifies requirements for an architecture description framework (ADF), an architecture description language (ADL), architecture viewpoints and model kinds in order to usefully support the development and use of an AD. This document specifies conformance to the requirements for an AD, ADF, ADL, architecture viewpoint and model kind. This document does not specify the processes, architecting methods, models, notations, techniques or tools by which an AD is created, utilized or managed. This document does not specify any format or media for recording an AD.